"There will be no formal meetings tomorrow… Only the meetings of experts, who will discuss technical issues," the source said.
A few minutes earlier, French Foreign Ministry political director for Iranian affairs Nicolas de Riviere said leaving the EU mission's building that the "P5+1 is over."
Meanwhile, Iran's Deputy Foreign Minister Abbas Araghchi said it was too early to make any conclusions, leaving the door open to bilateral talks on Monday.
Delegates from Russia, China, France and Germany, the remaining P5+1 group members, also took part in talks at the EU mission Sunday evening.
Suspicious that Tehran is developing nuclear weapons, the UN Security Council and a number of countries have handed down a series of sanctions on Iran. Meanwhile, Tehran maintains its uranium enrichment program is for peaceful purposes only.
Several rounds of P5+1 format talks have been held in the past, and the current deal requires a long-term comprehensive agreement on Iran's contested nuclear program to be reached by the end of July 2015.